阅读说明：本技术 波长转换装置 (Wavelength conversion device ) 是由 李日琪 杨立诚 黄文政 于 2021-01-04 设计创作，主要内容包括：一种波长转换装置包括漫反射层、基板及光致发光层。漫反射层具有相对的第一表面及第二表面,其中漫反射层包括亲水性黏合剂及多个亲油性黏合剂。基板位于漫反射层的第一表面。光致发光层位于漫反射层的第二表面。(A wavelength conversion device includes a diffusive reflective layer, a substrate, and a photoluminescent layer. The diffuse reflection layer has a first surface and a second surface opposite to each other, wherein the diffuse reflection layer comprises a hydrophilic binder and a plurality of oleophilic binders. The substrate is located on the first surface of the diffuse reflection layer. The photoluminescent layer is located on the second surface of the diffuse reflection layer.)

1. A wavelength conversion device, comprising:

a diffuse reflection layer having a first surface and a second surface opposite to each other, wherein the diffuse reflection layer comprises a hydrophilic binder and a plurality of oleophilic binders;

a substrate on the first surface of the diffuse reflection layer; and

a photoluminescent layer on the second surface of the diffuse reflection layer.

2. The wavelength conversion device according to claim 1, wherein the chemical structure of the hydrophilic binder has at least one hydroxyl group, and the chemical structure of each of the lipophilic binders has no hydroxyl group.

3. The wavelength conversion device according to claim 1, wherein each of the lipophilic binders is distributed in the diffusive reflective layer in a micro-encapsulated form.

4. The wavelength conversion device according to claim 3, wherein the diffuse reflection layer further comprises a plurality of reflective particles, and the reflective particles are distributed in the oleophilic binders.

5. The wavelength conversion device according to claim 4, wherein each of the oleophilic binder mixed with the reflective particles has a coefficient of thermal expansion between about 15ppm and about 40 ppm.

6. The wavelength conversion device according to claim 3, wherein each of the lipophilic binders has a diameter of about 1 μm to about 50 μm.

7. The wavelength conversion device according to claim 1, wherein the diffusive reflective layer further comprises a plurality of reflective particles distributed in the hydrophilic binder.

8. The wavelength conversion device according to claim 1, wherein the hydrophilic binder is present in an amount between about 30 wt% and about 45 wt% based on the total weight of the diffusive reflective layer.

9. The wavelength conversion device according to claim 1, wherein the lipophilic binders are present in an amount between about 5 wt% to about 20 wt% based on the total weight of the diffusive reflective layer.

10. The wavelength conversion device according to claim 1, wherein the diffusive reflective layer has a viscosity between about 10000cp to about 100000 cp.

Technical Field

The present invention relates to a wavelength conversion device.

Background

In recent years, optical projectors have been widely used in many fields and various places, such as schools, homes, and businesses.

In one type of projector, a laser source provides a first light incident on a fluorescent material, and then emits a second light. In this regard, a fluorescent material and a reflective material are coated on a fluorescent wheel, and the fluorescent wheel is driven by a motor to rotate at a high speed, and finally light reflected by the fluorescent wheel forms an image. With the increasing demand for brightness of optical projectors, how to make fluorescent materials and reflective materials exert better effects is an important issue at present.

Disclosure of Invention

The present invention is directed to a wavelength conversion device.

According to some embodiments of the present invention, a wavelength conversion device includes a diffusive reflective layer, a substrate, and a photoluminescent layer. The diffuse reflection layer has a first surface and a second surface opposite to each other, wherein the diffuse reflection layer comprises a hydrophilic binder and a plurality of oleophilic binders. The substrate is located on the first surface of the diffuse reflection layer. The photoluminescent layer is located on the second surface of the diffuse reflection layer.

In some embodiments of the present invention, the chemical structure of the hydrophilic adhesive has at least one hydroxyl group, and the chemical structure of the lipophilic adhesive has no hydroxyl group.

In some embodiments of the invention, the lipophilic binder is distributed in the diffusely reflective layer in the form of a micro-encapsulated structure.

In some embodiments of the present invention, the diffuse reflection layer further comprises a plurality of reflective particles, and the reflective particles are distributed in the oleophilic binder.

In some embodiments of the invention, the coefficient of thermal expansion of the oleophilic binder mixed with the reflective particles is between about 15ppm and about 40 ppm.

In some embodiments of the invention, the diameter of the lipophilic binder is between about 1 μm to about 50 μm.

In some embodiments of the present invention, the diffuse reflection layer further comprises a plurality of reflective particles, and the reflective particles are distributed in the hydrophilic binder.

In some embodiments of the present invention, the hydrophilic binder is present in an amount between about 30 wt% to about 45 wt% based on the total weight of the diffusive reflective layer.

In some embodiments of the present invention, the oleophilic binder is present in an amount between about 5 wt% to about 20 wt% based on the total weight of the diffusive reflective layer.

In some embodiments of the invention, the viscosity of the diffusive reflective layer is between 10000cp and 100000 cp.

According to the above embodiment of the present invention, since the wavelength conversion device includes the hydrophilic adhesive and the lipophilic adhesive uniformly distributed in the diffuse reflection layer, the tolerance of the diffuse reflection layer to high power irradiation and large temperature difference can be improved, so that the wavelength conversion device can exert better optical conversion performance.

The invention is described in detail below with reference to the drawings and specific examples, but the invention is not limited thereto.

Drawings

In order to make the aforementioned and other objects, features, and advantages of the invention, as well as others which will become apparent, reference is made to the following description taken in conjunction with the accompanying drawings in which:

FIG. 1A illustrates a perspective view of a wavelength conversion device according to some embodiments of the present invention;

FIG. 1B illustrates a cross-sectional view of the wavelength conversion device of FIG. 1A taken along line B-B', according to some embodiments of the present invention;

FIG. 2 is a graph showing the brightness of the excitation light reflected by the wavelength conversion devices of the comparative examples and the embodiment;

FIG. 3A is a schematic diagram illustrating the application of a wavelength conversion device to an optical module according to some embodiments of the invention; and

FIG. 3B is a schematic diagram illustrating the application of a wavelength conversion device to an optical module according to another embodiment of the invention.

Wherein the reference numerals

100 wavelength conversion device

110 base plate

111: surface

120 diffuse reflection layer

121 the first surface

122 reflective particles

123 second surface

124 hydrophilic adhesive

126 lipophilic adhesive

130 photo luminescent layer

132 optical particles

134 fluorescent powder

136 adhesive

200 color filter

300 light guide unit

1000 optical module

H is height

D diameter

L1 incident light beam

L2 excitation Beam

B-B' line segment

Detailed Description

In the following description, for purposes of explanation, numerous implementation details are set forth in order to provide a thorough understanding of various embodiments of the present invention. It should be understood, however, that these implementation details are not to be interpreted as limiting the invention. That is, in some embodiments of the invention, these implementation details are not necessary, and thus should not be used to limit the invention. In addition, some conventional structures and elements are shown in simplified schematic form in the drawings. In addition, the dimensions of the various elements in the drawings are not necessarily to scale, for the convenience of the reader.

As used herein, "about," "approximately," or "substantially" shall generally mean within 20%, within 10%, or within 5% of a given value or range. Numerical values set forth herein are approximate, meaning that the term "about", "approximately" or "substantially" is inferred unless expressly stated otherwise.

To improve the optical/thermal resistance properties (i.e., the ability to withstand high power illumination) and its tolerance to large temperature differences of wavelength conversion devices (e.g., fluorescent color wheels), the present invention provides a wavelength conversion device that includes a diffuse reflective layer with two binders. In a configuration of the wavelength converting device, the first type of binder is hydrophilic and the second type of binder is oleophilic, and the first type and the second type of binder are uniformly distributed in the diffusive reflective layer. Therefore, the bearing capacity of the diffuse reflection layer to high-power irradiation and large temperature difference can be improved, and the wavelength conversion device can exert better optical conversion efficiency.

Fig. 1A illustrates a perspective view of a wavelength conversion device 100 according to some embodiments of the present invention. FIG. 1B illustrates a cross-sectional view of the wavelength conversion device 100 of FIG. 1A taken along line B-B', according to some embodiments of the present invention. Please refer to fig. 1A and fig. 1B. The wavelength conversion device 100 includes a substrate 110, a diffusive reflective layer 120, and a photoluminescent layer 130. The diffusive reflective layer 120 has a first surface 121 and a second surface 123 opposite to each other. The substrate 110 is located on the first surface 121 of the diffusive reflective layer 120, and the photoluminescent layer 130 is located on the second surface 123 of the diffusive reflective layer 120. In other words, the substrate 110 and the photoluminescent layer 130 are located on opposite sides of the diffusive reflective layer 120. In some embodiments, the wavelength conversion device 100 is a reflective fluorescent color wheel that generates excitation light by absorbing a light beam (e.g., laser light). In detail, the light beam is absorbed by the photo-luminescent layer 130 to generate an excitation light, and the excitation light is further diffusely reflected by the diffuse reflection layer 120 to enter the diffuse reflection layer 120, and then emitted from the wavelength conversion device 100 for imaging. In some embodiments, the wavelength conversion device 100 is coupled to the motor through the drive shaft such that the wavelength conversion device 100 rotates with the drive shaft when the motor drives the drive shaft to rotate.

In some embodiments, the substrate 110 may be, for example, a sapphire substrate, a glass substrate, a borosilicate glass substrate, a floating borosilicate glass substrate, a fused silica substrate, or a calcium fluoride substrate, a ceramic substrate, an aluminum substrate, or a combination thereof. However, the material of the substrate 100 is not limited thereto, and the material of the substrate 110 may be adjusted according to actual needs. In some embodiments, the coefficient of thermal expansion of the substrate 110 is between about 20ppm and 100ppm, such that the substrate 110 can maintain its original dimensions while being subjected to a high power beam. In some embodiments, the surface 111 of the substrate 110 facing the diffuse reflection layer 120 may be further coated with a thin reflection layer to enhance reflection of a beam irradiated toward the substrate 110, or may be coated with a thin protection film to prevent damage to the surface of the substrate 110.

In some embodiments, the diffusive reflective layer 120 may include a plurality of reflective particles 122 configured to diffusively reflect excitation light excited by the photoluminescent layer 130. In some embodiments, the reflective particles 122 may include silicon dioxide (SiO)₂) Titanium dioxide (TiO)₂) Zinc oxide (ZnO), Boron Nitride (BN), zirconium dioxide (ZrO)₂) Alumina (Al)₂O₃) Or a combination thereof. In some embodiments, the reflective particles 122 are included in an amount of about 40 wt% to about 60 wt% based on the total weight of the diffusive reflective layer 120, so that a light beam irradiated on the diffusive reflective layer 120 has better reflectivity and enough space can be reserved for other components (e.g., a binder) to be distributed in the diffusive reflective layer 120. For example, when the content of the reflective particles 122 is less than about 40 wt%, the light beam impinging on the diffusive reflective layer 120 may not be efficiently reflected out of the wavelength conversion device 100 for imaging; when the content of the reflective particles 122 is higher than about 60 wt%, it may result in insufficient space in the diffusive reflective layer 120 to accommodate other components (e.g., a binder), such that the wavelength conversion device 100 has poor optical/thermal resistance characteristics and its tolerance to large temperature differences, which will be further described below.

In some embodiments, the diffusive reflective layer 120 can include a water-soluble hydrophilic adhesive 124. The hydrophilic binder 124 is the primary binder in the diffusive reflective layer 120 and is configured to tightly secure the reflective particles 122 in the diffusive reflective layer 120. It should be appreciated that the hydrophilic adhesive 124 does not interfere with the characteristics (e.g., wavelength) of the incident and reflected light. In some embodiments, the hydrophilic binder 124 may be further soluble in alcohols. For example, the hydrophilic binder 124 may include a water-soluble and/or alcohol-soluble silicone resin having a chemical structure with at least one hydroxyl group. Such hydrophilic adhesives can withstand high temperatures and, thus, light beams impinging thereon at high power. In some embodiments, the amount of the hydrophilic binder 124 is between about 30 wt% to about 45 wt% based on the total weight of the diffusive reflective layer 120, so that the diffusive reflective layer 120 has good optical/thermal resistance characteristics and high tolerance to large temperature differences. For example, when the content of the hydrophilic binder 124 is less than about 30 wt%, the diffusive reflective layer 120 may not have the ability to withstand high temperature; when the content of the hydrophilic binder 124 is greater than about 45 wt%, the content of the other binder (i.e., the lipophilic binder 126, which will be further described below) may be relatively low, resulting in the diffusive reflective layer 120 may not have the ability to withstand large temperature differences.

In some embodiments, the reflective particles 122 are further distributed in the hydrophilic binder 124, and the coefficient of thermal expansion of the hydrophilic binder 124 mixed with the reflective particles 122 is between about 600ppm to about 800 ppm. Thereby, the diffusive reflective layer 120 may have good optical/thermal resistance characteristics and high tolerance to large temperature differences. For example, when the coefficient of thermal expansion is less than about 600ppm, the diffusive reflective layer 120 may not have the ability to withstand high temperatures; when the thermal expansion coefficient is greater than about 800ppm, the other binder (i.e., the lipophilic binder 126, which will be further described below) may not compensate for (or reduce) the difference in thermal expansion coefficient between the hydrophilic binder 124 and the substrate 110, resulting in embrittlement or degradation of the diffusive reflective layer 120, further causing adverse effects on the wavelength conversion device 100 (e.g., unstable quality of the wavelength conversion device 100, low brightness of the wavelength conversion device 100, and poor reflectivity of the light beam).

In some embodiments, the diffusive reflective layer 120 may include a plurality of oleophilic oil-soluble binders 126. In some embodiments, the lipophilic binder 126 may further be hydrophobic (i.e., insoluble in water), which may also be referred to as a "hydrophobic binder 126" having different hydrophilic/hydrophobic characteristics than the hydrophilic binder 124. The lipophilic binder 126 may include an oil-soluble silicone resin having a chemical structure without hydroxyl groups. Such an oleophilic binder 126 may withstand large temperature differences impinging thereon. More specifically, when the wavelength conversion device 100 is switched between the operating state and the non-operating state, the diffusive reflective layer 120 may be impacted by a large temperature difference, and the oleophilic binder 126 may provide the ability to resist the large temperature difference impacting on the diffusive reflective layer 120 due to the softer (elastic) structure of the oleophilic binder 126 relative to the structure of the hydrophilic binder 124.

In some embodiments, the oleophilic binder 126 is present in an amount between about 5 wt% and about 20 wt% based on the total weight of the diffusive reflective layer 120 to provide the diffusive reflective layer 120 with good optical/thermal resistance characteristics and high tolerance to large temperature differences. For example, when the content of the oleophilic binder 126 is less than about 5 wt%, the diffusive reflective layer 120 may not have the ability to withstand large temperature differences; when the amount of oleophilic binder 126 is greater than about 20 wt%, the amount of hydrophilic binder 124 may be relatively low, resulting in the diffusive reflective layer 120 may not have the ability to withstand high temperatures. In a preferred embodiment, the oleophilic binder 126 is present in an amount between about 10 wt% and about 20 wt% to preferably achieve the above-described advantages.

Since the content of the lipophilic binder 126 is lower than that of the hydrophilic binder 124 and the hydrophilic/hydrophobic characteristics between the lipophilic binder 126 and the hydrophilic binder 124 are different, each lipophilic binder 126 can be distributed in the diffusive reflective layer 120 in a micro-capsule structure. In other words, each lipophilic binder 126 may self-assemble into micro-encapsulated structures having micron-scale dimensions, and the micro-encapsulated structures are tightly surrounded and encapsulated by the hydrophilic binder 124. In other words, the hydrophilic adhesive 124 coats the microcapsule structure along the outline of the microcapsule structure. In addition, the oleophilic adhesive 126 is soft (elastic) in structure, so the oleophilic adhesive 126 may be considered as a buffer structure filled in the hydrophilic adhesive 124 to be stretched and/or pressed during heating or cooling, thereby enhancing the elasticity of the entire diffusive reflective layer 120 so that the diffusive reflective layer 120 may withstand large temperature differences impinging thereon during switching of the operational and non-operational states of the wavelength conversion device 100. In addition, the diffusive reflective layer 120 containing such an oleophilic binder 126 is not susceptible to brittle fracture after curing. In some embodiments, each oleophilic binder 126 may be substantially circular in shape, and each oleophilic binder 126 may have a diameter D between about 1 μm and about 50 μm. Thereby, the oleophilic binder 126 may be uniformly distributed in the diffusive reflective layer 120 and thus provide the ability to resist large temperature differences impinging on the diffusive reflective layer 120. For example, when the diameter D of each lipophilic binder 126 is less than about 1 μm, the lipophilic binder 126 may not be able to act as a buffer structure to withstand large temperature differences; when the diameter D of each oleophilic binder 126 is greater than about 50 μm, only one oleophilic binder 126 may occupy a majority of the height H of the diffusive reflective layer 120 (e.g., the height H of the diffusive reflective layer 120 may be about 100 μm), and thus the oleophilic binder 126 may not be uniformly distributed in the diffusive reflective layer 120, resulting in poor ability of the diffusive reflective layer 120 to withstand large temperature differences. In a preferred embodiment, the diameter D of each oleophilic binder 126 may be between about 5 μm and about 30 μm, to preferably achieve the advantages described above.

In some embodiments, the reflective particles 122 are further distributed in an oleophilic binder 126, and each oleophilic binder 126 mixed with the reflective particles 122 has a coefficient of thermal expansion between about 5ppm to about 40 ppm. Thereby, the diffusive reflective layer 120 may have good optical/thermal resistance characteristics and high tolerance to large temperature differences. For example, when the thermal expansion coefficient is less than about 5ppm, the diffuse reflection layer 120 may not have the capability of withstanding high temperature; when the thermal expansion coefficient is greater than about 40ppm, the lipophilic binder 126 may not effectively compensate for the difference in thermal expansion coefficient between the hydrophilic binder 124 and the substrate 110, resulting in embrittlement or degradation of the diffusive reflective layer 120 to further adversely affect the wavelength conversion device 100 (e.g., unstable quality of the wavelength conversion device 100, low brightness of the wavelength conversion device 100, and poor reflectivity of the light beam). It should be appreciated that, because the plurality of reflective particles 122 are included in the oleophilic binder 126, the oleophilic binder 126 may be considered to be capable of reflecting light, although the oleophilic binder 126 itself does not interfere with the characteristics (e.g., wavelength) of the incident and reflected light. In some embodiments, the oleophilic binders 126 in the diffusive reflective layer 120 may have different sizes, wherein a larger oleophilic binder 126 may include more reflective particles 122 and a smaller oleophilic binder 126 may include fewer reflective particles 122. In other embodiments, a larger oleophilic binder 126 may include fewer reflective particles 122, and a smaller oleophilic binder 126 may include more reflective particles 122.

In some embodiments, the diffusive reflective layer 120 has a viscosity between about 10000cp and about 100000cp, depending on the concentration of the reflective particles 122 and the oleophilic binder 126. More specifically, during the fabrication of the wavelength conversion device 100, the solution to form the diffusive reflective layer 120 may be applied to the surface 111 of the substrate 110 at room temperature. It should be appreciated that when the viscosity of the diffusive reflective layer 120 is less than about 10000cp, the diffusive reflective layer 120 may have difficulty in controlling its coating range due to its high fluidity; when the viscosity of the diffusive reflective layer 120 is greater than about 100000cp, the diffusive reflective layer 120 may be difficult to coat due to its low fluidity.

In some embodiments, the photoluminescent layer 130 may include optical particles 132 configured to enhance the diffuse reflection of the excitation light. In some embodiments, the characteristics of the optical particles 132 distributed in the photoluminescent layer 130 may be substantially the same as those of the reflective particles 122 distributed in the diffusive reflective layer 120, and thus will not be described in detail below. In some embodiments, the photoluminescent layer 130 may include a plurality of phosphors 134, wherein the phosphors 134 may be, for example, silicate phosphors, nitride phosphors, Y having a garnet structure₃Al₅O1₂(YAG)、Tb₃Al₅O1₂(TAG) or Lu₃Al₅O1₂(LuAG) phosphor, or a combination thereof. In some embodiments, the phosphor 134 is included in an amount of about 65 wt% to about 85 wt% based on the total weight of the photoluminescent layer 130, so as to effectively convert the light beam irradiated on the photoluminescent layer 130 into the excitation light. For example, when the content of the phosphor 134 is less than about 65 wt%, the light beam may not be efficiently converted; when the content of the phosphor 134 is more than about 85 wt%, the phosphor 134 may be difficult to be fixed on the substrate 110.

In some embodiments, the photoluminescent layer 130 may include a binder 136. The adhesive 136 may fix the optical particles 132 and the phosphor 134 to the substrate 110. In some embodiments, the binder 136 may be a water-soluble hydrophilic binder. In a further embodiment, the properties of the binder 136 distributed in the photoluminescent layer 130 may be substantially the same as the properties of the hydrophilic binder 124 distributed in the diffusive reflective layer 120, and thus will not be described in detail below. In addition, the adhesive 136 may protect the optical particles 132 and the phosphor 134 to prevent the optical particles 132 and the phosphor 134 from precipitating, thereby improving the overall optical quality of the wavelength conversion device 100. The content of the binder 136 is between about 15 wt% and 35 wt% based on the total weight of the photoluminescent layer 130, so that the optical particles 132 and the phosphor 134 can be stably fixed on the substrate 110. For example, when the content of the binder 136 is less than about 15 wt%, the optical particles 132 and the phosphor 134 may be difficult to fix on the substrate 110; when the content of the binder 136 is higher than about 35 wt%, there may be insufficient space in the photoluminescent layer 130 to accommodate the optical particles 132 and the phosphor 134.

In the following description, the features of the present invention will be described more specifically with reference to wavelength conversion devices of some comparative examples and some embodiments of the present invention. It is to be understood that the materials used, the masses and proportions, the processing details and the processing procedures may be varied as appropriate without departing from the scope of the inventive concept. Therefore, the present invention should not be construed restrictively by the wavelength conversion device of the embodiment described below. The ratio of the composition to each composition in the wavelength conversion devices of the comparative examples and examples is listed in the following table. The diffusive reflective layer of each of the comparative examples and examples was coated on the substrate and cured at a temperature of about 200 ℃, and the photoluminescent layer of each of the comparative examples and examples was coated on the diffusive reflective layer at a temperature of about 200 ℃.

Watch 1

First, the wavelength conversion devices of the comparative example and the example were tested at a large temperature difference. More specifically, each wavelength conversion device is placed in an environment having an initial temperature of about 300 ℃ and then the temperature is momentarily lowered to about 25 ℃. The test results showed that the diffuse reflection layer in the wavelength conversion device of comparative example 1 peeled off and cracked, whereas the diffuse reflection layer in the wavelength conversion devices of comparative example 2, example 1, and example 2 remained intact in its original state and did not peel off and cracked. It can be seen that, since the wavelength converting devices of comparative examples 2, 1 and 2 include a lipophilic binder in the diffusive reflective layer thereof, the wavelength converting devices of comparative examples 2, 1 and 2 can withstand a large temperature difference impinging thereon.

Next, the luminance of the excitation light reflected by the wavelength conversion devices of the comparative examples and the examples was measured. More specifically, each wavelength conversion device is irradiated with a light beam having a power of about 450W, and then the light flux ratio (hereinafter also referred to as "luminance") of the excitation light to the incident light is measured. Fig. 2 is a diagram illustrating the brightness of the excitation light reflected by the wavelength conversion devices of the comparative example and the embodiment. Please refer to Table I and FIG. 2. The measurement results showed that the luminance of the excitation light reflected by the wavelength conversion devices of examples 1 and 2 was about 101% and 98%, respectively, that is, almost 100%. It is thus understood that the wavelength conversion devices of examples 1 and 2 can exhibit good optical conversion performance. On the other hand, the luminance of the excitation light reflected by the wavelength conversion device of comparative example 2 was about 91%, that is, relatively low, due to the content of the oleophilic binder in the diffusive reflective layer. In detail, since the content of the lipophilic binder is greater than about 20 wt%, the content of the hydrophilic binder may be relatively low, so that the diffusive reflective layer may not have the capability of withstanding high temperature, thereby resulting in poor light reflection capability, as shown in fig. 2.

Fig. 3A shows a schematic diagram of the application of the wavelength conversion device 100 to the optical module 1000 according to some embodiments of the present invention. Fig. 3B is a schematic diagram illustrating the application of the wavelength conversion device 100 to the optical module 1000 according to another embodiment of the present invention. Please refer to fig. 3A and fig. 3B. The optical module 1000 includes a wavelength conversion device 100, a color filter 200, and a plurality of light guide units 300. The wavelength conversion device 100 is configured to convert an incident light beam L1 into an excitation light beam L2. The color filter 200 is configured to realize the dispersion of the incident light beam L1 and the excitation light beam L2. In some embodiments, the color filter 200 may be a neutral density filter (ND filter), but the invention is not limited thereto. The light guide unit 300 is configured to guide an incident light beam L1 and an excitation light beam L2 passing therethrough. In some embodiments, the light guide unit 300 may be an optical lens, but is not limited to the invention. In some embodiments, at least one of the light guide units 300 may be disposed between the wavelength conversion device 100 and the color filter 200. The color filter 200 shown in fig. 3A allows an incident light beam L1 to pass therethrough. On the other hand, the color filter 200 shown in fig. 3B may reflect the incident light beam L1, and may further make the excitation light beam L2 incident, and may also pass the excitation light beam L2 reflected by the wavelength conversion device 100.

According to the above embodiment of the present invention, since the wavelength conversion device includes the hydrophilic adhesive and the lipophilic adhesive uniformly distributed in the diffuse reflection layer, the tolerance of the diffuse reflection layer to high power irradiation and large temperature difference can be improved, so that the wavelength conversion device can exert better optical conversion performance. Wavelength conversion devices of the present invention having two types of binders are less susceptible to embrittlement during heating or cooling or after curing, as compared to conventional wavelength conversion devices having only one type of binder (i.e., a hydrophilic binder).

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it should be understood that various changes and modifications can be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.